Solenoid having a two-piece armature



2 Sheets-Sheet 1 G. H. HORST SOLENOID HAVING A TWO-PIECE ARMATURE Dec.14, 1965 Filed June 14, 1965 Dec. 14, 1965 V G. H. HoRs'r 3,223,802

SOLENOID HAVING A Two-PIEcE ARMATURE Filed June 14, 1963 v 2Sheets-Sheet 2 United States Patent O 3,223,802 SOLENOID HAVING ATWG-PIECE ARMATURE Gunter H. Horst, Arcadia, Calif., assignor toSchulzTool and Manufacturing Co., San Gabriel, Calif., a corporation ofCalifornia Filed June 14, 1963, Ser. No. 287,896 `Claims. (Cl. 200-98)This invention relates generally to electromechanical devices andparticularly relates to a solenoid which is capable of exerting arelatively large force during the initial movement of the armature andthereafter a relatively small force during the remainder of the armaturetravel.

For some applications solenoids are required which must overcome a largeinitial resistance to the movement of the armature. After this initialresistance to the armature movement is overcome, only a relatively smalllforce is required for the remainder of the Itravel of the armature. Forexample, the solenoid may be required to open or close a valve. When alarge fluid pressure acts on the valve, there may be a very largeinitial resistance in opening the valve. Once the valve has been openedto a certain extent only a small force is necessary to move the valve tothe fully open position.

The same is true for certain latching relays of the type Where twosolenoids pull the relay from one fixed position to another. Thelatching or detent mechanism may be purposely made in such a manner thatthe relay is locked by a large force so that the relay is able towithstand large acceleration forces.

The solenoid of the present invention will be explained in connectionwith a latching relay to illustrate the problernv which the solenoid ofthe invention is designed to solve. However, it will `be understood thatthe solenoid of the invention may be used for other purposes, forexample, for opening or closing fluid valves.

- In a conventional solenoid wherethe armature moves through arelatively large distance, the initial magnetic force attracting thearmature is generally low. This is due to the fact that the armature isspaced from the attracting solenoid a relatively large distance andtherefore Athe magnetic force is initially low. On the other hand, atthe end of the travel of the armature, the attracting force increasessubstantially because the armature is closer to the solenoid.

Thus, a conventional solenoid provides the smallest attracting forceduring its initial travel where the largest force may be required forsome applications. In order to obtain a sutliciently large attractingforce with a conventional solenoid during the initial travel of thearmature it may be necessary to increase the electric power supplied tothe solenoid winding and to increase the size and weight ofthe entiresolenoi This may not be possi-ble for certain applications, particularlyfor air-borne latching relays.

It is accordingly an object of the present invention to provide asolenoid of relatively light weight and which is capable of exerting arelatively large force during the initial movement of its armature andthereafter a relatively small force during the remainder of the travelof the, armature.

Another object of the present invention is to provide a solenoid. of thetype referred to which requires little electric power for its operation.

A further object of the present invention is to provide asolenoid of thecharacter referred to cooperating with a detent mechanism for a relaywhich locks the relay against very substantial acceleration forces foruse with satellites and the like which are subjected to largeacceleration forces upon launching and change of attitude.

A solenoid, in accordance with the present invention,

provides, when energized, a relatively large force during the initialportion of movement of its armature and a relatively small force duringthe remaining portion of movement of its armature to overcome an initiallarge resistance to the armature movement.

The solenoid of the invention includes a solenoid winding which isadapted to be energized and which is of cylindrical shape to provide ahollow interior space. A core shell of magnetizable material may beprovidedand may surround the cylindrical surfaceof the winding, one Hatsurface of the winding, and may extend partially into the interior spaceof the solenoid winding.

There is further provided a movable armature for the solenoid which isadapted to -be attracted by the winding and the armature shell when thewinding isenergized. This armature includes two elements. shaped dapperdisposed adjacent the free flat surface of the winding and whichprovides the initial large force of the solenoid. The flapper is spaceda relatively small distance from the solenoids attracting surface sothat'it develops initially a large force.

The second element of the armature consists of a plunger which ismechanically coupled to the flapper. The plunger is disposed in theinterior space of the solenoid and is adapted to be attracted by thesolenoid winding. This plunger is spaced from the center of the core arelatively large distance and provides the relatively small force whichmoves the armature for the remainder of its travel.

The novel features that are considered characteristic of this inventionare set forth with particularly in the appended claims. The inventionitself, however, both as t0 its organization and method of operation, aswell as additional objects and advantages thereof, will best beunderstood from the following description when read in connection withthe accompanying drawings, in which:

FIG. 1 is a longitudinal sectional View, partly in elevation of alatching relay including two solenoids in accordance with the presentinvention, the relay being shown in one of its locked positions;

FIG. 2 is a longitudinal sectional view, parts being shown in elevation,similar to that of FIG. 1 but illustrating the relay in the other one ofits locked positions;

FIG. 3 is a cross-sectional view taken on line 3 3 of FIG. 1 andillustrating particularly the relay armature with its brushes andcontacts;

FIG. 4 is a longitudinal sectional view on an enlarged scale of one ofthe solenoids of the relay. of FIG. 1;

FIG. 5 is a sectional View on an enlarged scale illustrating the detentmechanism of the latching relay of FIG. l; and

FIG. 6 is a schematic representation and circuit diagram of the relaywith its solenoid windings.

Referring now to the drawings, and particularly FIGS. 1 to 3, there isillustrated a double solenoid or latching relay embodying two solenoidsin accordance with the present invention.

The latching relay generally includes a main housing 10, two end caps 11and 12, a switch armature 14 which is reciprocated by two solenoids 15and 16 which are of identical construction. The switch armature 14 isalso provided with a detent mechanism 17 which is illustrated in greaterdetail in FIG. 5.

The main housing 10 is as shown in FIG. 3and 1s top portion 18. housing10 preferably is made of two portions 20 and 21 for ease of assembly.The upper housing portion 20 may be provided with an outer projection22while the lower housing portion 21 has a corresponding innerprojection 23. This permits the two housing portions to be readilysealed together, as will be The'rst is a discmore fully explainedhereinafter. The top 18 of the main housing may be provided with twoelongated depressions 24 disposed on either side of a central projection25. A plurality of screws 26 may extend through the depressed mainhousing portions 24 for connecting thereto electric leads. A screw 27extends through the central projection 25 of the main housing and servesas a bearing for a spring 30 which urges a conical detent 31 downwardly.

The main housing is provided withtwo laterally extending cup-likeprojections 33 engageable with corresponding cylindrical recesses 34 inthe two end caps 11 and 12. In this manner the main housing 10 may besecured to the two end caps 11 and 12.

Since the two end caps 11 and 12 are identical, only one of them willnow be described. The end cap 11 as shown in FIG. 3, is of substantiallyrectangular cross-section and forms an internal cylindrical space 35 inwhich the solenoid is disposed. The end cap 11 may also be provided witha threaded bolt 36 having its head molded into the end cap 11 with thethreaded portion extending outwardly for securing the latching relay toa suitable chassis or support.

Before describing the solenoids 15 and 16 of the invention, the switcharmature 14 and associated parts will now be described.

The switch armature 14 consists of a suitable insulating material andgenerally has the shape of a triangular prism, as shown particularly inFIG. 3, having a at top portion 37.

The switch armature 14 is provided with a central cylindrical opening 38extending therethrough. A central shaft 40 extends through the switcharmature 14 and is connected 4to the two armatures of the two solenoids15 and 16, as will be more fully described hereinafter. The switcharmature 14 is secured to the shaft 40 by two snap discs 41 which maysnap into suitable recesses in the shaft 40 and which are disposed in atcylindrical recesses 42 at either end of the switch armature 14. Thus,the switch armature 14 is iirmly secured to the central shaft 40. As aresult, the switch armature 14 and its central shaft 40 are reciprocatedupon energization of the two solenoids 15 and 16 in sequence.

The switch armature 14, as illustrated, is designed to provide twodouble-pole, double-throw switches. However, it will be understood thatinstead of two, three or more such switches, or a single switch may beprovided. Furthermore, instead of providing a double-pole, doublethrowswitch, it is also feasible to provide a single-pole double-throwswitch.

To this end, the switch armature 14 is provided with two contact strips43 and 44. Each of the two contact strips 43 and 44 extend over thethree triangular-shaped side walls of the switch armature 14, but doesnot extend over the fiat top surface 37. Three contact brushes 45, 46and 47, cooperate with the contact 43. Similarly, three brushescooperate with the contact 44 of which brush 48 is shown in FIGS. l and2. The detailed construction of the brushes, such as 45 through 48, willbe subsequently explained.

The contact strip 43 consists of three connected portions 50, 51 and 52cooperating respectively with the three brushes 45, 46, and 47.Preferably, the contact portions 50, 51 and 52 are embedded in theswitch armature 14 so that they are ush with the outer surface thereof.In the position of the relay of FIG. 1, brush 45 is in contact with thecontact portion 50. Similarly, the brush 46 is in contact with thecontact portion 51. However, the brush 47 is out of engagement with thecontact portion 52. On the other hand, when the relay is in the positionof FIG. 2, brush 45 is out of contact with the contact portion 50 whilethe brushes 46 and 47 are respectively in contact with the contactportions 51 and 52.

As a result, an electric circuit connected between brushes 45 and 46will be closed with the relay in the position of FIG. 1 and open in theposition of FIG. 2. On the other hand, an electric circuit connectedbetween brushes 46 and 47 will be open when the relay is in the positionof FIG. 1 but will be closed when the relay is moved into the positionof FIG. 2. Accordingly, brushes 45 to 47 contact strip 43 to form adouble-pole, doublethrow switch.

It will be noted that the contact portion 51 is wide enough so its brush46 remains in contact therewith regardless of the position of the relay.It will now be apparent that the contact 44 is made in the same manneras the contact 43 and provides -two closed contacts in one position ofthe relay and two other closed contacts in the other position of therelay. Accordingly, further description of the contact 44 is not deemedto be necessary.

The respective six brushes such as 45 through 48 are mounted in asuitable brush holder 54 shown particularly in FIG. 3. The brush holder54 is preferably made of three separate pieces 55, 56 and 57 mainly forease of assembly. The outer surface of the brush holder 54 is generallycylindrical and tits into the generally cylindrical internal recess 58of the main housing 10. As shown particularly in FIG. 3, the brushholder 54 has three projections 60, each forming an elongated pocket 61for receiving the respective brushes 45 through 47. Each of the brushesis outwardly biased by a bias spring 62 in the recess 61 which ispreferably a coil spring. Each of the brushes 45 through 48 may, forexample, consist of a piece of sheet metal which has bent into asubstantially U-shape with an elongated central projection 63 whichcontacts the respective contacts 43 or 44.

The switch armature 14 is preferably locked in its two positions by thedetent mechanism generally indicated at 17. The detent mechanismincludes a movable detent member 31 having a conical tip 64, which mayhave a at end 65 shown particularly in FIG. 5. This detent cone 31 ispressed downwardly by the force of the spring 36) bearing against thescrew 27. The top portion 37 of the switch armature 14 has a recessedportion 66 which is generally flat and is provided with two conicalrecesses 67 and 68 with which the detent cone may engage. Thus, in FIG.1, the detent cone 31 engages the conical recess 67 while in FIG. 2, itengages the recess 68. The detailed operation of the detent mechanismwill be explained hereinafter in connection with FIG. 5.

Turning now to the two solenoids 15 and 16, it will be noted that thesolenoids are of identical construction and therefore only one of themwill be described. In this connection, reference is particularly made toFIG. 4 showing an enlarged View of the solenoid 15. The solenoid 15includes a solenoid winding 70 which is of cylindrical shape andprovided with an internal cylindrical recess 71. The solenoid winding 70is surrounded by a core shell generally indicated at 72. The core shell72 may be made of two separate pieces 73 and 74 for ease of manufacture.Thus, the core shell piece 73 is of generally cup shape and surroundsthe cylindrical outer surface 75 of the solenoid winding 70 and one ofits fiat surfaces 76.

The other core shell piece 74 has a central cylindrical portion 77 whichtogether with the core shell portion 72 forms a cup. The core shellportion 74 extends partially into the cylindrical hollow space 71 formedby the solenoid winding 70. This portion 78 is of generally cylindricalshape and is provided with an outer cylindrical recess 80 andintermediate cylindrical recess 81 of smaller diameter and an innerconical recess 82. A plunger 83 forms part of the armature of thesolenoid 15. The other portion of the solenoid armature is formed by aflapper 84.

The plunger 83 has a shape complementary to that of the inner orcylindrical core shell 78. Thus, the plunger 83 has an outer cylindricalportion 85 followed by a second or intermediate cylindrical portion 86of smaller diameter which in turn is followed by a third cylindricalportion 87 of still smaller diameter. The inner end of the plunger 83 isformed by a conical portion 88. Thus, itwill be seen that when theplunger 83 is attracted upon energization of the solenoid 15, it willsnugly lill the respective recesses 80, 81 and 82` of the core shellportion 78.

The plunger 83 is also provided with a central threaded recess 90 facingthe llapper 84. The central shaft 40 is provided with external threads91 so that the plunger 83 may be threaded into the end of the centralshaft 40. Thus, it will be seen that the plunger 83 is rigidly connectedto the central shaft 40 as is the armature 14.

The flapper 84 is of annular disc shape and is coextensive with theouter portion 92 of the core shell 72 and with the facing surface 93 ofthe solenoid winding 70. The ilapper 84 is provided with a centralannular disc or insert 95 which preferably consists of a nonmagnetic orinsulating material as shown. The central annular insert 95 may have anouter, central cylindrical projection 96 cooperating with an annularrecess 97 in the flapper 84 so that the flapper 84 and the annularinsert 95 maybe securely connected.

The annular insert 95 has a central opening 98 through which the shaft40 extends. Keyed to the shaft 40 is a disc 100 disposed in an annularrecess 101 in the insert 95. The recess 101 is open toward the plunger83. Thus, it will be seen that when the apper 84 moves toward the leftas shown in FIG. 4, it will force the shaft 40 to move along with thellapper. On the other hand, the plunger 83 is free to continue theleftward movement because the disc 100 will move out of its recess 101thus permitting further travel of the plunger 83 and shaft 40 even afterthe flapper 84 abuts the solenoid surface 93.

As will be explained more fully hereinafter, the distance between theopposing surface 93 of the solenoid winding 70 and the surface 103 ofthe flapper 84 is much less than the distance the plunger 83 has totravel until it abuts the central core shell portion 78. The purpose ofthis arrangement will be explained hereinafter.

The shell 72 is preferably disposed in a cup shape shell 105 whichconsists of a nonrnagnetic material.

Before describing in detail the operation of the relay illustrated inthe drawings, it will be convenient at this time to describe thepreferred materials of which the relay is made. Thus, the main housingand the end caps 11 and 12 may be made from an insulating plasticmaterial such, for example, as a polycarbonate. A polycarbonate is apolymer derived from bisphenol A or 4,4 dihydroxy diphenyl propane. Thiscompound has the chemical formula Such a polycarbonate is sold in thetrade under the name of Lexan by General Electric Company. This plasticmaterial may readily be molded and can be cheaply made in massproduction. It is also characterized by great impact strength.

The two housing portions and 21 may be joined together by a suitablecement, by heat sealing or in any other expedient manner. Lexan permitsalso to join the two housing portions by applying a solvent to thesurfaces to be joined. The two housing portions may then be put togetherand are joined when the solvent dries.

Preferably, the brush holder 54 is also made of Lexan. Similarly, thethree brush holder portions 55, 56 and 57 may be joined together in themanner previously outlined. Also, the switch armature 14 preferablyconsists of Lexan.

It is also preferred to provide a coating 106 over the exposed surface93 of the solenoid winding 70 and the corresponding exposed surface ofthe core shell 72. To this end, the Lexan may be dissolved in a suitablesolvent and a layer applied which may be one or two mils thick after ithas dried. The advantage of this Lexan coating 106 is its great impactstrength which will withstand the impact of the flapper 84. In addition,the Lexan coating 6. 93 breaks up the residual magnetic ux or magneticcircuit which may exist after the solenoid has beendeenergized. It alsoreduces the shock of the impact which might cause deterioration of thedesired magnetic hysteresis curve.

The conical detent 31 may also be made of Lexan. Preferably, however,the conical detent 31 is made of selflubricating material. under thename of Nylotron GS. Nylotron GS is compounded together with nylon and asuitable lubricant such as graphite or molybdenum disulphide. NylotronGS is a plastic material which can be readily molded. and which isself-lubricating to reduce wear.

Preferably, the plunger 83 is guided and lubricated by a guide tube thesolenoid winding 70 and adjacent the inner core shell portion 78.Preferably, the plunger guide tube 107 is also made of Nylotron GS so asto lubricate the plunger and reduce Wear. Alternatively, the guide tube107 may lbe made of Teflon or `any other suitable material.

The shell 106 is preferably made of brass or some other nonmagneticmaterial serving the purpose to confine the magnetic lines or ux. Bothcore shell portions 72 and 74 may be molded or sintered from powderediron. Alternatively, they may be made from a magnetizable iron such asArmco ingot iron. The main shaft 40 may, for example, consist of brass.

The various shorting brushes 45 through 48 may consist of any conductingmaterial which has `a flaking action under wear. Thus, the shortingbrushes may be made of or may have their central projections 63 platedwith an alloy known as coin silver which consists of 92% silver and 8%copper. Alternatively, the shorting brushes may consist of or be platedwith an alloy known as nickel silver which includes 81% copper and 18%nickel. The shorting brushes may also consist of palladium, rhodium,platinum or gold or may be plated therewith. All these metals have theproperty that they are resistant to chemical action and hence thecontact surface tends to remain clean. They also have a flaking actionwhich further helps to maintain a clean contact surface.

The contacts 43 and 44 which has pits or depressions. Thus, the contactsmay consist of or be plated with molybdenum. Alternatively, tungsten orstainless steel may be used which also provide a pitted surface. It isalso feasible to make the contacts of copper or brass which is nickelplated.

The operation of the relay illustrated in the drawings will now beapparent. Let it be assumed that the relay is originally in the positionshown in FIG. l. Subsequently, the solenoid Winding ofthe solenoid 15may be energized. Thereupon, the apper 84 and the plunger 83 will beattracted to move the armature 14 from the right to the left into theposition shown in FIG. 2. As a result, an electric circuit connectedbetween the brushes 45 and 46 will be opened. At the same time, anelectric circuit connected between the brushes 46 and 47 will be closed.The same operation ltakes place with the second set of three shortingbrushes.

This has been schematically illustrated in FIG. 6, which illustrates theposition of the switches corresponding to the relay position of FIG. l.Thus, an elec-tric circuit connected to the brushes 4S and 46 is closedwhile that between brushes 46 and 47 is opened. It will be understoodthat electric conductors connect each of the six brushes with one of thesix screws 26. Two of the screws 26 interconnect respectively thewindings of solenoids 15 and 16 to permit sequential energizationthereof.

Considering in greater detail the operation of the solenoid of theinvention. Referring now to FIG. 4, when the solenoid winding 70 becomesenergized, the dapper 84 is attracted primarily by the solenoid winding70 and secondarily by the core shell portion 73. Since the distancebetween the apper 84 and the solenoid winding is relatively short, theilapper is attracted with a relatively large force. This force issufficient to move the conical Such a material is sold in the trade 107disposed in the cylindrical recess 71 of may be made of any metal 7detent 31 from its recess 68 onto the flat surface 66 of the switcharmature 14.

By way of example, it may be assumed that the spring 30 presses theconical detent 31 downwards with a force of 14.2 pounds. It may also beassumed that the angle of the conical depression 67 or 68 amounts to 45while the angle of the conical tip 64 of the detent may amount to 40.Thus, it can be calculated that the conical detent 31 may be moved tothe right or to the left out of either of its conical recesses with aforce of 10.2 pounds. It will be noted that, due to the difference ofthe angles of the conical recesses 67 or 63 and of the conical tip 64 ofthe detent, the detent essentially has a line contact with its recess.This obviously facilitates moving the detent out of its recess.

It may also be assumed that the width of the conical recess 67 or 68 is0.015 inch or 15 mils. At the same time, it may be assumed that thedistance between the edges of the two recesses is 0.075 inch. Thus, thedetent must travel 0.090 inch from conical recess 67 to recess 63 orvice versa. The travel of liapper 84 under these assumptions may, forexample, amount to 9 mils. This distance is suicient to move the conicaldetent 31 out of its recess until its flat tip 65 fully engages the atsurface 66 as shown in FIG. 5. On the other hand, the travel of theflapper 84 may amount to 0.090 inch, that is, the entire travelnecessary to move the detent from one recess to the other.

It may further be assumed that the coefficient of friction between theLexan surface 66 of the switch armature 14 and the Nylotron surface ofthe iiat tip 65 of the detent amounts to 0.01. Since the weight actingon the ldetent is 14.2 pounds, a force of 0.01 times 14.2 or 0.142pounds corresponding to 2% ounces is needed to move the armature 14 oncethe detent 31 rides over the flat surface 66.

These calculations show that the initial pull exerted by the solenoidfor a distance of 0.009 inch must amount to 10.2 pounds. For theremainder of the travel of 0.090 inch, a force slightly in excess of 2%ounces is suflicient to move the armature from one position to theother. In other words, this is the small force required of the plunger83.

The insert 95 of the flapper 84 is preferably made of a nonmagneticmaterial such, for example, as Lexan. The purpose of this is that therewill be no magnetic force tending to pull the plunger 83 toward theright of FIG. 4.

It may be noted that the magnetic lield after the solenoid winding hasbeen energized requires a certain amount of time to build up. Until thefull magnetic field has been built up, the solenoid armature will notmove because it has to overcome a relatively large force. Once themagnetic field has been built up to its full strength, the movement willbe very rapid until eventually the flapper 84 hits the Lexan coating106. Thereafter, the plunger 87 is attracted by the magnetic eldexisting in the interior 71 of the winding which is assisted by thecentral core shell 74. The stepped cylindrical shape of the plunger 83is for the purpose of increasing the surface, thereby to intercept alarge number of magnetic flux lines by the plunger. Thus, the plunger S3will pull the switch armature through the major portion of its travelbut with a very small force which is sufficient to move the armatureuntil the detent again locks it.

It may be noted that the solenoid winding 70 may, for example, have aresistance of 500 ohms and may be energized with a voltage of 20 volts.Thus, 0.04 ampere or 40 milliarnperes will ow in the coil. The totalpower consumption is accordingly 0.8 watt.

It may be noted that the spring 30 through the detent 31 exerts a largeforce on the aramture 14. This force is taken up by the central shaft 40and is distributed by the respective plungers 83 onto their guide tubes107. Since the guide tubes 107 are preferably self-lubricating, therewill be little frictional resistance.

o ci

The solenoid of the invention can readily overcome a force ofacceleration of the order of 100 g, where g is the acceleration of thegravitational field of the earth. Assuming that the movable armature hasa total weight of 1.6 ounces or less: With an acceleration of 100 g,this weight would be 10 pounds which is still less than the weightrequired to pull the detent cone 31 out of its recess. Obviously, thearmature weight could be made smaller or the spring force larger so thatthe resulting device can be designed to withstand a higher accelerationif needed.

The relay may be assembled in the following manner:

At rst, the armature 14 is secured to the central shaft 40 by the twosnap discs 41. Then, the snap ring 100 is put on the shaft after theflapper 84 with its central insert has been put between the plunger andthe armature. Subsequently, the two plungers are screwed on the ends ofthe shaft 40. Thereafter, the various shorting brushes with theirsprings are inserted into their pockets 60. The two solenoids 15 and 16with their shells 105 are assembled in their respective end caps 11 and12. Now, the three brush holder portions 55, 56 and 57 are assembledabout the armature. Then, the conical detent 31 with its spring 30 isinserted into the main housing 10 which may now be assembled about thebrush holder. Subsequently, the two end caps are put over the mainhousing and secured thereto. The relay is now ready for operation.

While the solenoid of the invention has been explained in connectionwith a latching relay, it will be understood that the solenoid 0f theinvention may also be used for other applications with or without adetent mechanism. For example, the solenoid of the present invention maybe used in connection with a fluid valve which requires a large initialforce for opening the valve against the force of iiuid pressure.

There has thus been disclosed a solenoid which will develop a relativelylarge force during the initial travel of its armature and thereafter arelatively small force. Such a solenoid may be used, for example, inconnection with a latching relay designed to withstand large forces ofacceleration or in connection with fluid valves. The solenoid can bedesigned of relatively light weight and requires a relatively smallelectric energy for its operation. Both of these factors are of primeimportance for air-borne applications or for satellites where bothelectric power and weight are at a premium. This is accomplished bymaking the armature of two portions, one of which develops the initiallarge force While the other is designed to move the armature through thebulk of its travel against a low frictional resistance.

The invention and its attendant advantages will be understood from theforegoing description. It will be apparent that various changes may bemade in the form, construction and arrangement of the parts of theinvention without departing from the spirit and scope thereof `orsacrificing its material advantages, the arrangement hereinbeforedescribed being merely by way of example. I do not wish to be restrictedto the specific form shown or uses mentioned except as defined in theaccompanying claims, wherein various portions have been separated forclarity of reading and not for emphasis.

I claim:

1. A solenoid providing, when energized, a relatively large force duringthe initial portion of movement of its armature and a relatively smallforce during the remaining portion of movement of its armature toovercome an initial large resistance to the armature movement, saidsolenoid comprising:

(a) a single solenoid having a winding adapted to be energized and ofcylindrical shape providing a hollow interior space and having at leastone flat surface;

(b) a movable aramture for said solenoid and adapted to be attracted bysaid solenoid winding when said winding is energized, said armatureincluding (1) a disc-shaped apper disposed adjacent one of the flatsurfaces of said winding and adapted to be attracted thereby forproviding the initial large force, said apper being spaced a relativelysmall distance from said solenoid, said armature further including (2) aplunger mechanically coupled'to said llapper, said plunger beingdisposed in the interior space of said solenoid and adapted to beattracted thereby, said plunger providing the relatively small force.

2. A solenoid providing, after energization, a relatively large forceduring the first small portion of movement of its armature andthereafter a relatively small force to overcome an initial largeresistance to the movement of its armature, said solenoid comprising:

(a) a single solenoid having a winding adapted to be energized andforming a hollow cylinder providing la hollow central space and havingat least one flat surface;

(b) a flapper of magnetizable material disposed adjacent one of the atfaces of said winding, and said flapper being adapted to be attracted bysaid solenoid winding upon energization thereof with a relatively largeforce;

(c) a shaft secured to said apper in such a manner that said shaft ispulled by said flapper upon eneregization of said winding but ispermitted to continue moving in the same direction after said flapperabuts said winding; and

(d) a plunger of magnetizable materialsecured to said shaft, saidiapper` and said plunger forming together the armature of said solenoid,said plunger being disposed in said hollow space and being adapted t beattracted by said winding upon energization thereof, said plunger havinga movement which is appreciably larger than that of said apper, theforce exerted by said plunger being relatively small cornpared tothatexerted by said flapper.

3. A solenoid providing, when energized, a relatively large forceduringthe initial portion of movement of its armature and a relativelysmall force vduring the remaining relatively large portion of movementof its armature to overcome an initial large resistance to the armaturemovement, said solenoid comprising:

(a) a single solenoid having a winding adapted to be energized and ofcylindrical shape providing ahollow interior space and having twoopposed flat surfaces;

(b) a core shell surrounding the cylindrical surface of said winding,one flat surface thereof and extending partially into the interior spacethereof;

(c) a movable armature `for said solenoid and adapted to be attracted bysaid solenoidwinding and core shell whensaid winding is energized,saidarmature including (1) a disc-shaped dapper disposed adjacent thefree flat surface of said Winding and adapted to be attracted therebyfor providing the initial large force, said flapper being spaced arelatively small distance from said solenoid, and said armature furtherincluding (2) a plunger mechanically coupled to said apper, said plungerbeing disposed in the interior s-pace'of` said` solenoid and adapted tobe attracted by said core shell, said` plunger being spaced from saidcorel shell a relatively large distance for providing the relativelylsmall force over a relatively large distance, and said flapper having arelatively large air gap with said plunger.

4. A solenoid providing, after energization, a relatively, large forceduring its rst portion of movement and thereafter a relatively smallforce to overcome an 10 initial large resistance to the movement of itsarmature, said solenoid comprising:

(a) a single solenoid having a winding adapted to be energized andforming a hollow cylinder to provide a hollow central space and havingtwo opposed flat surfaces;

(b) a core shell of magnetizable material surrounding the cylindricalsurface and one flat face of said winding, said shell having a portiondisposedy in the hollow space of said winding;

(c) a cup-shaped'member of nonmagnetizable material surrounding saidwinding and said shell to confine the magnetic linx;

(d) a apper of magnetizable material disposed adjacent the other flatface of said Winding, said flapper being adapted to be attracted by saidsolenoid winding upon energizaton thereof with a relatively large force;

(e) a shaft secured to said dapper in such a manner that said shaft ispulled by said iiapper upon energization of said winding but ispermitted to continue moving in the same direction after said flapperabuts said Winding; and

(f) a plunger of magnetizable material secured to said shaft, saidflapper and said plunger forming together the armature of said solenoid,said plunger bein-g normally spaced from said shell portion and beingdisposed in said hollow space and being adapted to be attracted therebyupon energization of said Winding, said plunger having a movement whichis appreciably larger than that of said liapper before engagement withsaid shell and winding, respectively, the force exerted by said plungerbeing relatively small compared to that exerted by said flapper.

5. A solenoid providing, when energized, a relatively large force duringthe initial small portion of movement 0f its armature and a relativelysmall force during the remaining relatively large portion of movement ofits armature to overcome an initial large resistanceito the armaturemovement, said solenoid comprising:

(a) a single solenoid having a winding adapted to be energized and ofcylindrical shape providing a hollow interior space and having twoopposed flat surfaces;

(b) a core shell surrounding the cylindrical surface of said winding,lone flat surface thereof and extending partially into the interiorspace thereof, said shell portion disposed in said interior space havinga central recess forming a conical tip followed by a plurality ofcylindrical spaces of successively larger diameter toward its outer end;

(c) a movable armature for said solenoid and adapted to be attracted bysaid solenoid Winding and core shell when said Winding is energized saidarmature including (l) a disc-shaped iiapper disposed adjacent the freeflat surface of said windingk for providing the initial large force,said apper being spaced a relatively small distance from said solenoidand beingadapted to be attracted thereby, and said armature furtherincluding (2) a plunger mechanically coupled to said flapper, saidplunger being disposed in the interior space of said solenoid and havinga shape to fit snugly the central recess of said shell portion and beingadapted to be attracted by said core shell, said plunger being spacedfrom said core shell a relatively large distance for providing therelatively small force over a relatively large distance.

6. A solenoid providing, after energization, a relatively large forceduring its first portion of movement and thereafter a relatively smallforce to overcome an initial ll large resistance to the movement of itsarmature, said solenoid comprising:

(a) a solenoid having a winding adapted to be energized and forming ahollow cylinder to provide a hollow central space and having two opposediiat surfaces;

(b) a core shell of magnetizable material surrounding the cylindricalsurface and one at face of said winding, said shell having a portiondisposed in the hollow space of said winding;

(c) an annular llapper of magnetizable material disposed adjacent theother flat face of said winding and coextensive with said winding andouter core shell, said llapper being adapted to be attracted by saidsolenoid winding upon energization thereof with la relatively largeforce;

(d) a shaft;

(e) an annular insert of nonmagnetizable material secured to said apperand disposed about said shaft, said insert having an open recess facingsaid hollow space of said winding;

(f) a disc secured to said shaft and abutting against said recess insaid insert to pull s-aid shaft upon attraction of said apper andpermitting said shaft to continue moving in the same direction aftersaid flapper abuts said winding; and

(g) -a plunger of magnetizable material secured to said shaft, saidflapper and said plunger forming together the armature of said solenoid,said plunger being normally spaced from said shell portion and beingdisposed in said hollow space and being adapted to attract thereby uponenergization of said winding, said plunger having a movement which isappreciably larger than that of said flapper before engagement with saidshell and winding, respectively, the force exerted by said plunger beingrelatively small compared to that exerted by said flapper.

7. A double solenoid and associated detent mech-anism comprising:

(a) a rst and a second solenoid spaced from each other, each solenoidincluding ('l) a single solenoid winding adapted to be energized andforming a hollow cylinder to provide a hollow central space and havingtwo opposed at surfaces;

(2) a core shell of magnetizable material surrounding the cylindricalsurface and one flat face of said winding, said shell having a portiondisposed in the hollow space of said winding',

(3) an annular apper of magnetizable material disposed adjacent theother at face of said winding, said apper being adapted to be attractedby said solenoid winding upon energization thereof with a relativelylarge force;

(i4) a plunger of magnetizable material, said flapper and said plungerforming together the armature of said solenoid, said plunger beingnormally spaced from said shell portion and disposed in said hollowspace and being adapted to be attracted thereby upon energization ofsaid winding, said plunger having a movement which is appreciably largerthan that of said flapper before engagement with said shell and winding,respectively, the force exerted by said plunger being relatively smallcompared to that exerted by said apper;

(b) a common shaft secured to said plungers and to said flappers in sucha manner that said shaft is pulled by one of said flappers uponenergization of its winding but is permitted to continue moving in thesame direction after said flapper abuts its winding; and

(c) a detent mechanism coupled to said shaft for locking said shaft inone of two positions after energization of one of said solenoids.

8. A double solenoid and associated detent mechanism comprising:

(a) a rst and -a second solenoid spaced from each other, each solenoidincluding (l) a single solenoid winding adapted to be energized andforming a hollow cylinder to provide a hollow central space and havingtwo opposed flat surfaces;

(2) -a core shell of magnetizable material surrounding the cylindricalsurface and one flat face of said winding, said shell having a portiondisposed in the hollow space of said winding;

(3) an annular flapper of magnetizable material disposed adjacent theother ilat face of said winding, said llapper being adapted to beattracted by s-aid solenoid winding upon energization thereof with arelatively large force;

(4) a plunger of magnetizable material, said flapper and said plungerforming together the armature of said solenoid, said plunger beingnormally spaced from said shell portion and disposed in said hollowspace and being adapted to be attracted thereby upon energization ofsaid winding, said plunger having a movement which is 1appreciablylarger than that of said dapper before engagement with said shell andwinding, respectively, the force exerted by said plunger beingrelatively small compared to that exerted by said flapper;

(b) a common shaft secured to said plungers and to said flappers in such-a manner that said shaft is pulled by one of said flappers uponenergization of its winding but is permitted to continue moving in thesame direction after said flapper abuts its wind- (c) an element securedto said shaft and having a at surface and two spaced conical recesses;

(d) a detent member disposed stationary with respect to said element andhaving a conical end portion and a flat tip adapted to move over said atsurface upon sequential energization of said solenoids, said conical endportion being adapted to seat in one or the other of said conicalrecesses; and

(e) spring means for urging said detent member against said llat surfaceand said recesses with an appreciable force.

9. A double solenoid and associated detent mechanism comprising:

(a) a first and a second solenoid spaced from each other, each solenoidincluding (l) a solenoid winding adapted to be energized and forming ahollow cylinder to provide a hollow central space and having two opposedflat surfaces;

(2) a core shell of magnetizable material surrounding the cylindricalsurface and one flat face of said winding, said shell having a portiondisposed in the hollow space of said winding;

(3) an annular flapper of magnetizable material disposed adjacent theother flat face of said winding, said flapper being adapted to beattracted by said solenoid winding upon energization thereof with arelatively large force;

(4) a plunger of magnetizable material, said apper and said plungerforming together the armature of said solenoid, said plunger beingnormally spaced from said shell portion and disposed in said hollowspace and being adapted to be attracted thereby upon energization ofsaid winding, said plunger having a movement which is appreciably largerthan that of said apper before engagement with said shell and winding,respectively, the force exerted by said plunger being relatively smallcompared to that exerted by said flapper;

(b) a common shaft secured to said plungers and to said appers in such amanner that said shaft is pulled by one of said appers upon energizationof its winding but is permitted to continue moving in the same directionafter said ilapper abuts its wind- 111s;

(c) an element secured to said shaft and having a flat surface and twospaced conical recesses;

(d) a detent member disposed stationary with respect to said element andhaving a conical end portion and a flat tip adapted to move over said atsurface upon sequential energization of said solenoids, said conical endportion being adapted to seat in one or the other of said conicalrecesses, the angle of the cone of said conical end portion being lessthan the angle of said conical recesses, whereby said detent member hassubstantially a line contact with said recesses; and

(e) spring means for urging said detent member against said flat surfaceand said recesses with an appreciable force.

10. A double solenoid and associated detent mechanism comprising:

(a) a first and a second solenoid spaced from each other, each solenoidincluding (1) a solenoid winding adapted to be energized and forming ahollow cylinder to provide a hollow central space and having two opposedfiat surfaces;

(2) a core shell of magnetizable material surrounding the cylindricalsurface and one flat face of said winding, said shell having a portiondisposed in the hollow space of said winding;

(3) an annular apper of magnetizable material disposed adjacent theother flat face of said winding, said apper being adapted to beattracted by said solenoid winding upon energization thereof with arelatively large force;

(4) a plunger of magnetizable material, said flapper and said plungerforming together the armature of said solenoid, said plunger beingnormally spaced from said shell portion and disposed in said hollowspace and being adapted to be attracted thereby upon energization ofsaid winding, said plunger having a movement which is appreciably largerthan that of said flapper before engagement with said shell and winding,respectively, the force exerted by said plunger being relatively smallcompared to that exerted by said apper;

(b) a common shaft secured to said plungers and to said appers in such amanner that said shaft is pulled by one of said flappers uponenergization of its winding but is permitted to continue moving in thesame direction after said ilapper abuts its winding;

(c) an element secured to said shaft and having a fiat surface and twospaced conical recesses;

(d) a detent member disposed stationary with respect to said element andhaving a conical end portion and a ilat tip adapted to move over said atsurface upon sequential energization of said solenoids, said conical endportion being adapted to seat in one or the other of said conicalrecesses;

(e) spring means for urging said detent member against said flat surfaceand said recesses with an appreciable force; and

(f) a guide tube for each of said plungers disposed in said hollowcentral space of said winding, said guide tubes providing a low-frictionbearing for said plungers, said plungers and guide tubes taking up theforce exerted by said spring means.

References Cited by the Examiner UNITED STATES PATENTS 626,919 6/ 1899Medary. 1,257,613 2/1918 Kocourek. 2,895,090 7/1959 Short 317-188BERNARD A. GILHEANY, Primary Examiner.

40 ROBERT K. SCHAEFER, Examiner.

1. A SOLENOID PROVIDING, WHEN ENERGIZED, A RELATIVELY LARGE FORCE DURINGTHE INITIAL PORTION OF MOVEMENT OF ITS ARMATURE AND A RELATIVELY SMALLFORCE DURING THE REMAINING PORTION OF MOVEMENT OF ITS ARMATURE TOOVERCOME AN INITIAL LARGE RESISTANCE TO THE ARMATURE MOVEMENT, SAIDSOLENOID COMPRISING: (A) A SINGLE SOLENOID HAVING A WINDING ADAPTED TOBE ENERGIZED AND OF CYLINDRICAL SHAPE PROVIDING A HOLLOW INTERIOR SPACEAND HAVING AT LEAST ONE FLAT SURFACE; (B) A MOVABLE ARMATURE FOR SAIDSOLENOID AND ADAPTED TO BE ATTRACTED BY SAID SOLENOID WINDING WHEN SAIDWINDING IS ENERGIZED, SAID ARMATURE INCLUDING (1) A DISC-SHAPED FLAPPERDISPOSED ADJACENT ONE OF THE FLAT SURFACES OF SAID WINDING AND ADAPTEDTO BE ATTRACTED THEREBY FOR PROVIDING THE INITIAL LARGE FORCE SAIDFLAPPER BEING SPACED A RELATIVELY SMALL DISTANCE FROM SAID SOLENOID,SAID ARMATURE FURTHER INCLUDING (2) A PLUNGER MECHANICALLY COUPLED TOSAID FLAPPER, SAID PLUNGER BEING DISPOSED IN THE INTEIROR SPACE OF SAIDSOLENOID AND ADAPTED TO BE ATTRACTED THEREBY, SAID PLUNGER PROVIDING THERELATIVELY SMALL FORCE.